University of Oradea, University Street, no. 1, Oradea, Romania, Ph.D. student in Geography, * * * * * *

Transcription

1 Analele Universităţii din Oradea, Seria Geografie Year XXIII, no. 2/213 (December), pp ISSN , E-ISSN Article no THE PRECIPITATIONS REGIME IN THE HYDROGRAPHIC BASIN CRIŞUL NEGRU Viorel GALIŞ University of Oradea, University Street, no. 1, Oradea, Romania, Ph.D. student in Geography, Abstract: The precipitations regime in the hydrographic basin Crişul Negru This paper presents the main characteristics of the precipitations regime from the hydrographic basin Crişul Negru based on meteorological observation data from 1 stations spread across the entire basin. The analysis was developed based on the classical methodology of processing the meteorological data presented with a climatological purpose in various specialty studies. The study developed reveals that the pluviometric regime depends on a number of factors such as the air movement, topography and local conditions, actually known from previous studies, but this paper distinguishes itself as a novelty through its values that are statistically concrete and correct, all calculated for the main parameters that characterize one of the most important elements of climate: precipitations. Key words: precipitations regime, hydrographic basin Crişul Negru * * * * * * INTRODUCTION Due to a variety of genetic factors (the movement of air masses, topography, thermal and dynamic convection, local conditions), the precipitations represent the element with the greatest variability in both time and space, which is why we attempt, in this paper, a detailed analysis of its regime. HISTORY OF RESEARCH To date, no complex and complete climatic study has been conducted on the Crişul Negru basin, similar to the one concerning the basin of Crişul Repede (Măhăra et al., 1999; Moza, 29), so there is information only about the study of wider areas. Among these we mention the doctoral dissertations published by: Cristea (24) which marks the climate risks from the Criş basin and which mentions certain climatic elements, including temperature, all analyzed using data from several weather stations in the Crişul Negru hydrographic basin; Gaceu (25) who analyzes a double period (4 years) and refers to climate and climate risks in Vlădeasa and Bihor Mountains, including the thermal regime, a more detailed and highly parameterized analysis but which focuses less on our study area (with the weather stations form Stâna de Vale and Ştei); Şerban (21) who, through a detailed analysis, refers to climate hazards from the Corresponding Author

2 364 Viorel GALIŞ Western Plain which is located north of Mureş and captures through the Salonta, Holod, Chişinău Criş, Ineu stations aspects concerning air temperature. Climatic aspects concerning the precipitations regime from the Crişul Negru hydrographic basin were presented in other articles: Măhăra, 1981; Gaceu, 1998; Gaceu & Vlaicu, 21; Gaceu & Linc, 25; Măhăra & Gaceu, 25; Gaceu et al., 25; Gaceu, 26; Dumiter & Gaceu, 28. DATA AND METHODOLOGY The Crişul Negru hydrographic basin covers all three levels of relief (plains, hills, mountains), an aspect considered when selecting the weather stations for a better measurement of air temperature characteristics. Thus, we chose 1 meteorological stations (figure 1) distributed as follows: Vlădeasa (1836 m), Stâna de Vale (118 m), Zece Hotare (642 m), Moneasa (73 m) for the mountain area Dumbrăviţa de Codru (586 m), Ştei (278 m) for the hilly area, Holod (163 m), Salonta (95 m), Chişineu Criş (96 m), Ineu (11 m). Unfortunately, the climate analysis was more difficult due to the lack of homogeneity of the data, the stations being set up in different stages, during the ( Ştei, Vlădeasa 18, Chişineu Criş, Holod), the 197 s 197 ( Moneasa, Stâna de Vale and Ineu), anii 198 ( Dumbrăviţa de Codru and Salonta), the 2 s (Zece Hotare, Moneasa, Salonta, Ineu), which is why we used data from the period, a continuum 3 years, thus respecting the climate research methodology. Due to the process started in Romania in the 2 s to dispense with the weather stations (the question of the automation and computerization of the National Meteorological system arose) 4 of the 1 stations in the Crişul Negru basin (Zece Hotare, Moneasa, Salonta, Ineu) have 7 years short data, but the remaining 6 stations (Vlădeasa 18, Stâna de Vale, Ştei, Dumbrăviţa de Codru, Holod, Chişineu Criş) have continuous data for 3 years so they are representative according to the WMO norms and are uniformly distributed on the surface of the studied basin (Kostin & Pokrovskaia, 1964; Belozerov & Fărcaş, 1971; Arlery et al., 1973; Marin, 1986; Fărcaş, 1988; Bogdan & Niculescu, 1999; Gaceu, 22). Thus, we tried to conduct a comparative analysis as objective as possible, which is why we used pure data, without interfering with statistical processing which can sometimes drift away from the factual reality, a goal accomplished due to the existence of six meteorological stations with data complete for 3 years. RESULTS AND DEBATES THE ANNUAL AVERAGE PRECIPITATIONS The meteorological observation data analyzed for the period or for certain stations (table 1), indicates a territorial distribution of the annual average precipitation amounts, certain details being given by the exposure of the Crişul Negru hydrographic basin to the western and northwest air masses. Therefore, the moist oceanic air masses enter the basin drained by Crişul Negru (Beiuş Depression) closed at north and south by the Pădurea Craiului Mountains and by the Pădurea Craiului Mountains, thus meeting the orographic barrier of the Bihor and Vlădeasa Mountains and being forced to have an upward Codru-Moma motion, adiabatically being cooled to the dew point temperature which leads to generating large amounts of precipitations on the western slopes" (Gaceu, 25; Moza, 29). The fact is proved by the differential distribution of the precipitations which increase from west to east together with the increase in altitude, from 545. at Chişineu Criş, to 68. at Ştei, to 81. at Dumbrăviţa de Codru, to at Zece Hotare, to at Moneasa, to at Stâna de Vale. But this increase takes place only until the Stâna de Vale station (11 m) because after this altitude the precipitations start to decrease while the altitude continues to increase ( at the Vlădeasa station located at 1836 m) as the highest peaks are below the condensation level and, as Vlădeasa for example, they lose the precipitations intake brought by a part of the lower and medium clouds (table 1, figure 2).

3 The Precipitations Regime in the Hydrographic Basin Crişul Negru 365 Figure 1. The location of the meteorological stations in the Crişul Negru hydrographic basin Figure 2. The distribution of annual average precipitation amounts in the Crişul Negru hydrographic basin

4 366 Viorel GALIŞ Table 1. Annual average precipitation amounts in the Crişul Negru hydrographic basin Source: Data from the A.N.M. Archives Station Altitude (m) Period Annual average () Vlădeasa Stâna de Vale Moneasa Zece Hotare Dumbrăviţa de Codru Ştei Holod Ineu Chişineu Criş Salonta Deviation of the annual average precipitation amounts from the multiannual average The average precipitation amount is the "norm" or the average calculated over several years, but this value can vary from year to year and thus we calculated the value and the direction of these deviations for each year using the Hellman criterion (Table 2). Table 2. The pluviometric character of the months and years according to the Hellman criterion Source: Data from the A.N.M. Archives Average monthly deviation (%) Average annual deviation (%) Remarks >. > 2. excessively rainy very rainy rainy moderately rainy normal moderately dry dry very dry <. < 2. excessively dry From table 2 we can observe that this criterion highlights the different types of time depending on the size of the deviation, ie: normal, less rainy, rainy etc., the limits of the annual deviation intervals being reduced to half as compared to the monthly ones, due to the fact thaht their oscillations are lower than the monthly one. In order to highlight the deviation of the annual average precipitation amounts from the multiannual average in the Crişul Negru hydrographic basin, the Hellman criterion was applied for the 1 stations located in the basin. According to this criterion, as in the case of the air temperature, most of the years are normal from the point of view of precipitations and have a frequency between 13.2% and 35.7% (Table 3). Most of these normal years happen in mountainous area of the basin (2% at Zece Hotare, 23.3% at Stâna de Vale, 28.% at Vlădeasa, 3.% at Moneasa and 35.7% at Dumbrăviţa de Codru ), and they happen less frequently in the plain areas (13.2% at Holod, 18.4% at Chişineu Criş, 2% at Salonta, 21.1% at Ineu) (table 3). The following years are the excessively dry ones, with frequencies between 7.1% at Dumbrăviţa de Codru and 25% at Moneasa, the highest frequency being met generally in the plain areas (2% at Salonta 23.7% at Chişineu Criş) (table 3 ). The excessively rainy years are more frequent in the plain areas (1% at Salonta, 12, at Ştei, 15,8% at Holod and Ştei, 18,4% at Chişinei Criş) than in the mountains (1% at Moneasa and

5 The Precipitations Regime in the Hydrographic Basin Crişul Negru 367 at Zece Hotare, 13,3% at Stâna de Vale, 16% at Vlădeasa), which emphasizes the moderator role of the mountain compared to the plains where the continental aspect is more pronounced (table 3). Table 3. The pluviometric character of the years in the Crişul Negru hydrographic basin, according to the Hellman criterion Source: Data from the A.N.M. Archives Station (Period) Vlădeasa ( ) years Stâna de Vale ( ) 32 years Moneasa ( ) 2 years Zece Hotare ( ) 1 years Dumbrăviţa de Codru ( ) 28 ani Ştei ( ) years Holod ( ) 43 years Ineu ( ) 19 years Chişineu Criş ( ) 49 years Salonta ( ) 2 years Total years The average frequency in the basin (%) Altitude. (m) Excessively Years rainy Freq% Very rainy Years Freq% Rainy Years Freq% Moderately Years rainy Freq% Normal Years Freq% Moderately Years dry Freq% Dry Years Freq% Very dry Years Freq% Excessively Years dry Freq% 8, The very rainy and very dry years have the lowest frequency. Thus, the very rainy years are almost missing in the mountains (only 8% at Vlădeasa) and in the plain areas they have a frequency between and 5.3% % (% at Chişineu Criş and Ineu, 4% at Ştei, 5% at Salonta, 5.3% at Holod), while the very dry years have a frequency between and 13% in the mountains (% la Moneasa şi Zece Hotare, 1% la Vlădeasa, 13.3% la Stâna de Vale) and between to 13.2% in the plain areas (% at Salonta, 5.3% at Chişineu Criş, 8% at Ştei, 1.5% at Ineu, 13.2% at Holod) (table 3). The rainy and dry years have a much higher frequency than the very rainy and very dry ones, ranging from 4 to 14%, correspondingly from to 13.3% (table 3). The moderately rainy and moderately dry years have similar frequencies both at the general level of the basin and on the floors of relief, ranging between 2 and 2%, correspondingly from to 2%. The average at the level of the basin is 9.9% for moderately rainy years and 6.9% for moderately dry years (table 3). In conclusion, Table 3 shows that in the Crişul Negru hydrographic basin the normal years predominate from a pluviometric point of view (21.8%), followed by excessively dry ones (14.9%) and the excessively rainy years (13.1%), the moderately rainy (9.9%) and the moderately dry (6.9%), the rainy ones (9.7%) and the dry ones (11.5%); the very rainy years (4%) and the very dry one (8.1%) have the lowest frequency. Moreover, the analysis shows that the rainiest years, with the largest positive deviations recorded at all stations in the Crişul Negru hydrographic basin were: 1966, 197, 1974, 198, 1981, 1999, 21, 25, with deviations between 383,4 at Chişineu Criş in 25, at Holod in 21, at Ştei in 197, at Stâna de Vale in 198, 594. at Vlădeasa in The driest years, with the largest negative deviations recorded throughout the

6 368 Viorel GALIŞ Crişul Negru hydrographic basin were: 1973, 1975, 1983, 1986, 199, 2 with negative deviations between at Chişineu Criş in 1973, at Holod in 2, at Ştei in 2, at Stâna de Vale in 1983, at Vlădeasa in 2. Therefore, the greatest deviations from the norm occurr in the area with the greatest potential for precipitations, and the smallest deviations appear in areas with the lowest potential for precipitation, which is also observed by Gaceu (25) for Bihor and Vlădeasa Mountains. THE MONTHLY AVERAGE PRECIPITATION Depending on the characteristics of the atmospheric circulation, on relief (altitude, slope orientation) and on other local conditions, precipitations vary from month to month. Thus, the lowest amount falls in winter during the January-March interval (table 4, figure 3, figure 4), as a result of the installation of the cold, heavy air which doesn t allow thermal convection. The driest month is February with 26.2 at Chişineu Criş in the plain area, 46.4 at Dumbrăviţa de Codru (the hill area) and 89 in the mountains at Stâna de Vale. An exception is the highest peaks represented by the Vlădeasa station where the minimum occurs in March (6.5 ). Table 4. The annual and monthly average precipitation amounts () from the Crişul Negru hydrographic basin Source: Data from the A.N.M. Archives Station Vlădeasa ( ) Stâna de Vale ( ) Moneasa ( ) Zece Hotare ( ) Dumbrăviţa de Codru ( ) Ştei ( ) Holod ( ) Ineu ( ) Chişineu Criş ( ) Salonta ( ) Alt (m) I II III IV V VI VII VIII IX X XI XII Annual average Month Since March, in general, the amount of precipitations increases in June when the main maximum occurs (82.9 in the plains of Chişineu Criş, 11.8 at Dumbrăviţa de Codru,in the hills area and at Stâna de Vale in the mountains) (table 4, figure 3, figure 7) caused by the humid air masses coming from the Atlantic, air masses strongly unstable because of the thermal convection dynamically induced at the contact with the mountain. Precipitations start to decrease in June, until October when the secondary minimum appears (38.4 at Chişineu Criş, 55.1 at Dumbrăviţa de Codru and at Stâna de Vale). In December, as a result of the intensification in the mediterranean cyclones activity, another secondary maximum occurs with 42.9 at Chişineu Criş, 68.4 at Dumbrăviţa de Codru and 159. in the mountains area (table 4, figure 2). In conclusion, in the Crişul Negru hydrographic basin area, during the year there are two maximums and two minimums in terms of precipitations: the main maximum and the main minimum are characteristic for the entire country and happen due to the continental climate of the country; the secondary maximum is determined by the mediteranean movements while the

7 The Precipitations Regime in the Hydrographic Basin Crişul Negru 369 secondary minimum in determined by the extention of the ridge of the Azoric anticyclone to this area, thus confirming the results of numerous reseaches concerning the precipitations regime for the entire country Topor, 1964; Topor, Stoica, 1965; Fărcaş, 1983, Bogdan & Niculescu, 1999; Geografia României I, 1983; Clima României, 28 etc. Vladeasa (1836 m) Stâna de Vale (118 m) Moneasa (73 m) Zece Hotare (642 m) Dumbravita de Codru (586 m) Stei (278 m) Holod (163 m) Ineu (11 m) Chisineu Cris (96 m) Salonta (95 m) Figure 3. The monthly average precipitation amounts () from the Crişul Negru hydrographic basin

8 37 Viorel GALIŞ Figure 4. The monthly average precipitation amounts () from the Crişul Negru hydrographic basin during February. Figure 5. The monthly average precipitation amounts () from the Crişul Negru hydrographic basin during June

9 The Precipitations Regime in the Hydrographic Basin Crişul Negru Vlădeasa 18 Stâna de Vale Moneasa Zece Hotare Dumbrăviţa de Codru Ştei Holod Ineu Chişineu Criş Salonta Figure 6. The monthly average precipitation amounts () from the Crişul Negru hydrographic basin during February Vlădeasa 18 Stâna de Vale Moneasa Zece Hotare Dumbrăviţa de Codru Ştei Holod Ineu Chişineu Criş Salonta Figure 7. The monthly average precipitation amounts () from the Crişul Negru hydrographic basin during June Table 5. The maximum amount of precipitations () during 24 hours and the monthly average Source: Data from the A.N.M. Archives Station Cant Vlădeasa Max (1836 m) Med Stâna de Max V. (118 Med m) Ştei Max (278m) Med Holod Max (163 m) Med Chişineu Criş (96 m) Max Med

10 372 Viorel GALIŞ THE MAXIMUM AMOUNT OF PRECIPITATIONS (MM) DURING 24 HOURS Knowing the maximum amount of precipitations during 24 hours is of special importance because it shows on one hand the character of the region s climate and, on the other hand, the high variability of the pluviometric regime (Pătăchie, 1974). The analysis was applied only for five meteorological stations, the most representative ones due to both the longest string of data and the geographic position (ie all levels of relief) from the entire Crişul Negru hydrographic basin: Vlădeasa, Stâna de Vale, Ştei, Holod, Chişineu Criş. The maximum amount of precipitations during 24 hours usually occurs during the warm season months when the Cumulonimbus and Cumulus congestus clouds develop, generating heavy rain and thus causing flooding, excess water in the soil, soil erosion, landslides etc. There are also many situations where the amount of precipitations in 24 hours is higher than the multiannual average of the month. This happened, for example, at Ştei in February 197, when in one day 41. of precipitations were registered, compared to the multiannual average of the month which was of 35.9 ; in October 1992, 49.8 of precipitations were registered at Ştei in one day, compared to that month s 44.8 average, at Stâna de Vale where, in 1996 October 19 there was a value of 128., compared to that month s average etc. (table 5, figure 8). 1 Vlădeasa Annual average The maximum during 24 hours 2 Stâna de Vale Annual average The maxiumum during 24 hours 1 Monthly average Ştei The maximum during 24 hours

11 The Precipitations Regime in the Hydrographic Basin Crişul Negru 373 Holod Monthly average The maxiumum during 24 hours 1 Chişineu Criş Monthly average The maxiumum during 24 hours Figure 8. The maximum amount of precipitations () during 24 hours and the monthly average in the Crişul Negru hydrographic basin CONCLUSIONS In the Crişul Negru hydrographic basin the pluviometric regime depends on a number of factors such as the movement of air masses, topography and local conditions. a) The movement of air masses determines the existence of two maximums and two minimums of precipitations: the main maximum and the main minimum are characteristic for the entire country and are mainly determined by the seasons, while the secondary maximum and minimum are mainly determined by the Mediterranean movements and by the extension of the ridge of the Azoric anticyclone to this area. b) The relief determines an increase in precipitations with the increasing altitude, up to a certain level which is, according to our data, at about 11 m, after which, even if the altitude increases, the precipitations decrease. Thus, are recorded in the hills of Chişineu Criş, at Stâna de Vale in the mountains and on the heights surrounding Vlădeasa. d) The local conditions (depressions, ridges, slopes orientation) determine deviations from the vertical pluviometric gradient in terms of annual or monthly quantities, but also in terms of the amount of precipitations during 24 hours. REFERENCES Arléry R., Grisollet H., Guilmet B. (1973), Climatologie. Méthodes et practiques, Gauthier-Villars Ed., Paris. Belozerov V., Fărcaş I. (1971), Îndrumător metodologic pentru lucrările practice. Bogdan Octavia, Niculescu Elena (1999), Riscurile climatice din România, Sega International, Bucureşti: 28. Cristea Maria (24), Riscurile climatice din bazinul hidrografic al Crişurilor, Editura Abaddaba, Oradea, 186 p. Dumiter Aurelia, Gaceu O. (28), Les caractéristiques du régime pluvial au aréa de la ville d Oradea, (Roumanie), Actes du colloque de Montpellier, Franţa, p: Fărcaş I. (1983), Probleme speciale privind climatologia României, partea I, Factorii climatogenetici, Curs litogr., UBB Cluj-Napoca: 295.

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